The impact of the surface acidity nature of the nanoparticles on the diffusion limited behavior of the glycidyl nano-UV-coatings driven by the microgelation process

Herein, two commercial grades of nanosilica particles with various surface acidities were incorporated into a glycidyl-based polyester acrylate resin. The effect of the surface acidity of the SiO2 nanoparticles on the photopolymerization-induced microgelation process was studied using electrochemical impedance spectroscopy technique. The diffusion-limited behavior was observed in both nano-UV-coatings loaded by two nano SiO2 particles with different surface acidity. The structural heterogeneity caused by the microgelation phenomenon was decreased as the highly-acidic nanoparticles were included in the photopolymeric matrix. The highest value of the pore resistance and the finite length Warburg resistance were obtained for the UV-coatings incorporated by the highly-acidic SiO2 nanoparticles. The apparent diffusion coefficient of Cl− through the microgel domains at the beginning of the immersion test was calculated to be 70 μm2/s for both coatings loaded by the slightly-acidic particles and highly-acidic particles.